What’s the one thing you can do now, that could shave 90-seconds off your 25 mile cycle times?
When it comes to cycling, everyone thinks it’s all about the training. The more training you do, the better you’ll be, right?
To some extent that’s true, but only to a point. After that, any improvements are much harder to come by.
That’s why I want to tell you about a far quicker way to improve your cycling speed – through aerodynamics. Here’s a quick story, to illustrate my point…
I have a friend who invested in a wind-tunnel test last year, hoping to shave a few seconds off his bike splits. The outcome?
For the same power output as before, he was able to ride 90-seconds faster for a 25-mile time trial. Wow, I thought.
Why such a huge improvement?
It’s a sad fact of cycling life that the faster, more powerful you are, the greater the resistance and the harder you’ve got to work to boost your speed.
As an example, at 25km/hr, around 70% of the effort that you’re generating is used to overcome air resistance. Increase that figure to 32km/hr and you’re looking at 85%.
That’s where aerodynamics comes in. The more slipstreamed you are – in other words, the more you can reduce drag – the faster you’ll move. In essence, this is free speed.
One of the clearest examples of the importance of aerodynamics on cycling speed derives from a study by aerodynamicist Bert Blocken that examined the efficiency of Chris Froome’s infamous super-tuck descending position.
Blocken compared Froome’s position with five other common aerodynamic positions and discovered the following:
The slowest was a back-upwards position; a horizontal back was 8% faster; Froome’s position 9% faster; a ‘back-down’ position 12%; the (Marco) Pantani position 14%; and, the fastest at 17%, a ‘safer’ top-tube version of Froome’s position.
In actual fact, the true best was a Superman position (24% faster) with the legs horizontal, but it was deemed too dangerous!
The unit of measurement for cycling aerodynamics is called CdA. Scores range upwards of zero. A brick might be a resistant 2.0, while teardrop-shaped bars can register an aero 0.005.
An elite triathlete with aero-bars measures 0.18-0.25, while a good amateur is more like 0.30.
Your aim as a cyclist is to generate a high wattage and low CdA. This too can be measured.
When Tony Martin won the 2011 World Time Trial Championships, his power output and aerodynamic drag (expressed as watts per m2 CdA) was calculated as 2,089.
This compared to 1,943 for Bradley Wiggins in second and 1,725 for Jakob Fuglsang in 10th.